Exchange and transport in animals Flashcards
What happens to the SA:V ratio when organisms get bigger?
The ratio gets smaller
What does a smaller SA:V ratio mean for organisms?
Cannot rely on diffusion and need to have specialised exchange surfaces and transport systems
Where is oxygen exchanged and why?
In the alveoli in the lungs; needed for respiration
Where is carbon dioxide exchanged and why?
Alveoli in lungs; waste product of metabolism
Where is water exchanged and why?
Nephrons in kidney; needed for cells to function properly
Where are dissolved food molecules exchanged and why?
Small intestine; needed for respiration
Where are mineral ions exchanged and why?
Small intestine; needed for cells to function properly
Where is urea exchanged and why?
Nephrons in kidney; waste of metabolism
Why do flatworms does not have a transport or exchange system?
Flatworm is very thin and flat so has a large SA:V ratio and so diffusion occurs at a much greater distance
What factors affect the rate of diffusion?
- SA (larger SA, faster diffusion)
- Concentration gradient (bigger difference in concentration, faster diffusion)
- Distance to move (substances move more quickly if they haven’t got far to move)
What does Fick’s law state?
Rate of diffusion ∝ (SA X Concentration difference)/Thickness of membrane
What does a.u. stand for?
Arbitrary units
Describe gas exchange in the alveoli
- Air breathed in
- CO2 in blood from body produced by respiring cells and very little O2
- O2 diffuses across capillary membrane out of alveolus and enters red blood cells
- O2 carried round the body in red blood cells
- Body cells use up O2 in respiration
- Body cells produce CO2 in respiration and is carried to the lungs
- CO2 diffuses into the alveolus and is breathed out
- Air breathed out
Why is the alveoli folded?
Increases SA for gas diffusion
What are alveoli?
Tiny air sacs in the lungs
Describe how arteries pump blood
- Muscle fibres are stretched
- They contract and press inwards
- Helps push blood towards capillaries
- Stretching and contracting causes pulse which can be felt at wrist and neck
Why do veins only have a thin layer of muscle fibres?
For efficient diffusion
What do the valves in the vein do?
Stop blood flowing away from the heart
Describe how the valves in veins contribute to blood flow to and from heart
- Open like double doors to let blood flow towards heart
- Close to stop blood flowing away from heart
Describe the structure of capillaries
- Very small blood vessels
- Very thin walls so substances can go through thin walls of a capillary
Which blood vessels carry blood back to the heart?
Veins
Which blood vessels go between the cells of the body?
Capillaries
Which blood vessels carry blood away from the heart?
Arteries
Describe how the three blood vessels carry blood to and from the heart
- Heart pumps blood into arteries
- Arteries carry blood away from heart
- Arteries divide into very thin vessels called capillaries
- Capillaries go between cells of the body
- Capillaries join up to make veins
- Veins have valves in them
- Veins carry blood back to the heart
What is the equation for respiration?
Glucose + Oxygen -> Water + CO2 + Energy
In which blood vessel is the blood pressure the highest?
Arteries
What does the relaxation of muscle in arteries reduce?
Reduces the variation in blood pressure and males blood flow smoothly
In which blood vessel is the blood pressure the lowest?
Veins
Why are capillary walls only 1 cell thick?
- Substances in blood are very close to cells
- Distance for diffusion with cells is as small as possible
Describe the flow of blood through the heart
- Vena cava brings deoxygenated blood from the body into the right atrium
- Right atrium contracts and forces blood through tricuspid valve into the right ventricle
- Right ventricle contracts and pumps blood through a valve and into the pulmonary artery
- Blood flows to the lungs where it becomes oxygenated
- Blood flows out of lungs into pulmonary vein
- Blood flows through vein to left atrium
- Flows through bicuspid valve to ventricle
- Out of left ventricle to aorta (main artery) and back to body
Why is the blood pumped through the heart twice?
- To be filled with O2
- To increase blood pressure as it is low from the pulmonary vein
What is the pulmonary circulation?
One circuit between the lungs and the heart
What is the systematic circulation?
One circuit between the body and the heart
What is plasma?
- Liquid part of the blood
- Carries blood cells through blood vessels
- Contains many dissolved substances, such as CO2 and glucose
What are white blood cells?
- Larger than red blood cells
- Have a nucleus
- Part of the immune system
- Attacks pathogens in the body
What are platelets?
- Fragments of larger cells
- Prevent blood loss
- No nucleus
- Causes blood to clot when blood vessel is damaged
- Clot blocks wound and prevents pathogens getting into blood
What are phagocytes?
White blood cells that surround and ingest pathogens and destroy them
What are lymphocytes?
White blood cells that produce chemical antibodies that attach to pathogens and destroy them
How does the structure of a red blood cell relate to its function?
- Contains haemoglobin = carries O2
- Biconcave shape = large surface area, making it easier for O2 to diffuse into and out of cell
- No nucleus = cell has room for more haemoglobin to carry more O2
What % of the blood is plasma, white blood cells & platelets and red blood cells?
- Plasma = 55%
- White blood cells and platelets = <1%
- Red blood cells = 45%
Why do the number of lymphocytes increase during infection?
- Pathogens cause infection
- Lymphocytes produce antibodies that attach to antigens on surface of pathogen and destroy them
What is the function of plasma?
Transports blood cells and digested food
What is the function of red blood cells?
Contains haemoglobin which transports O2 from the lungs to the tissues
What is the function of white blood cells?
- Lymphocytes make antibodies which destroy pathogens
- Phagocytes engulf pathogens
What is the function of platelets?
Fragments of cytoplasm that involved in clotting of blood which prevents blood loss and entry of microbes through cuts/wounds
How are bacteria destroyed by phagocytes?
- Phagocyte flows around bacteria and engulfs them
- Bacteria enclosed in a vacuole and digested
How do phagocytes reach bacteria?
- Blood capillary cut open
- Phagocytes squeeze through capillary wall
- Phagocytes surround bacteria and digest them
What is the formula for cardiac output?
CARDIAC OUTPUT = STROKE VOLUME X HEART RATE
What is stroke volume?
Volume of blood pumped out of blood in one heart beat (left ventricle)
What does it mean if a person has a large stroke volume?
More O2 can reach their muscles with less effort
What is cardiac output?
The amount of blood pumped out of the heart
What is heart rate?
How fast the heart beats, measured in beats/min
What does training/exercise increase?
-Size of heart
-Strength of heart muscles
-Force at which heart muscles contract
(All increases stroke volume)
What does a larger stroke volume mean for heart rate?
The larger the stroke volume, the smaller the increase in heart rate to give the same cardiac output (the heart does not have to beat as fast)
What is aerobic respiration?
Respiration that uses O2 from the air to release energy from glucose which produces CO2 and H2O
What is the equation for aerobic respiration?
C6H12O6 + 6O2 -> 6CO2 + 6H2O + ENERGY
What happens to your blood and muscle cells during exercise?
- Muscle cells respire faster so need more O2 and glucose and release more CO2
- Increased heart rate means blood is pumped faster around the body
- Blood takes O2 and glucose to cells faster and removes CO2 faster
Which respiration releases less energy: anaerobic or aerobic?
Anaerobic
What is the difference in glucose levels between the two types of respiration?
- Aerobic = glucose broken down completely
- Glucose only partly broken down to lactic acid
When does anaerobic respiration occur?
During high intensity exercise
What happens to the volume of O2 consumed during high intensity exercise?
Increases because of increased aerobic respiration
When does anaerobic respiration start?
Aerobic respiration increases until O2 cannot reach muscles any faster and so anaerobic starts but aerobic also continues
What is the equation for anaerobic respiration?
GLUCOSE -> LACTIC ACID + SOME ENERGY
What is lactic acid?
Substance produced during anaerobic respiration that is poisonous and causes cramps
How long does a person breathe heavily after exercise?
Until all the lactic acid has been broken down by the oxygen (happens in the liver)
What is the equation for exercise recovery?
LACTIC ACID + OXYGEN -> CO2 + H2O
What is EPOC?
- ‘Excess post-exercise oxygen consumption’ = the volume of O2 needed to break down the lactic acid after exercise, also called oxygen debt
- The amount of O2 needed after exercise has ended compared with resting rate
Which respiration type produces an EPOC?
Anaerobic
What is fermentation?
Anaerobic respiration in yeast
What are the similarities between the two types of respiration?
- Both involve enzymes
- Both release energy
- Both use glucose as a reactant/substrate
